The present invention pertains to batteries, and more particularly to batteries having a built-in indicator to communicate battery state of charge.
Consumers use batteries in many applications, such as portable electronic devices including radios, flashlights, clocks, compact disc players, cameras, cellular phones, electronic games, toys, pagers, computer devices, etc. Operation of such devices requires having sufficiently charged batteries in the device or available replacements. Inexpensive electronic devices typically give no indication of the remaining life in the batteries. Thus, the consumer generally has no warning of impending battery failure before the device stops operating.
Consumer batteries are generally used in such devices, consumer batteries being characterized as having a standard size and nominal terminal voltage and being relatively inexpensive. Examples of consumer batteries include batteries typically designated as an AAAA, AAA, AA, C, D, prismatic 9 V battery, and may further include larger batteries generally used in vehicles. A characteristic of consumer batteries is that they are generally designed for a broad range of devices rather than for a specific device.
Some consumer batteries provide simple thermo-chromatic labels for testing battery state of charge. However, such built-in battery testers have a number of disadvantages. First, thermo-chromatic labels are limited in accuracy, sometimes being as much as twenty percent off the state of charge of the battery due to factors such as manufacturing variability and temperature of the battery. Second, thermo-chromatic labels dissipate significant amounts of energy and are thus made to only provide an indication when manually activated by the consumer pressing the label. Thus, the consumer cannot readily inspect a battery but must undergo the inconvenience of removing a battery from its packaging or from a device and firmly press the thermochromatic label for a period of time.
More complex battery management functions have been developed for use in battery-powered electronic devices. For example, video camcorders and portable personal computers typically give a warning of impending shutdown due to a discharged battery, and may even estimate time remaining on the battery. However, such indication functions are relatively costly and complex electronic circuits that can add significantly to the cost to the electronic device. For example, the cost of a low performance microprocessor generally used in such circuits would be generally cost prohibitive in consumer batteries, as well as for inclusion in many inexpensive battery-powered devices. In addition, such circuits generally are applicable to only one type of battery, are too large to incorporate into the battery itself, and require that the electronic device be available and operable to provide an indication regarding the battery.
In some exotic applications such as aerospace vehicles, battery management functions may be incorporated into a battery system or packaging. Although space, weight, and power consumption may be factors of concern in such applications, the limitations imposed by the size constraints of a consumer battery are generally more demanding. Moreover, the cost for such circuits is typically not a concern in exotic applications. For low-cost consumer batteries, however, no such functionality is supported.
The present invention meets these and other needs with an indicating system incorporated into a battery container, the indicating system including an indicator controller that is responsive to the internal electrode voltage of the voltaic cell also within the battery container. The indicating system further includes an indicator that is controlled by the indicator controller. In some embodiments, an indicating system is provided that includes a pulse indicator and in other embodiments an analog indicator such as a bargraph.
In another aspect of the present invention, a consumer battery conforming to an outer dimension and a terminal voltage is provided with an indicating system that senses an electrode voltage of the voltaic cell, thereby controlling an indicator. The consumer battery can incorporate these features within a container having standardized dimensions.
In yet another aspect of the invention, a method for indicating a state of charge is provided that includes detecting an electrode voltage of a voltaic cell within a battery package containing a built-in integrated circuit, comparing the electrode voltage to a reference voltage, and indicating the state of charge when the electrode voltage falls below a reference voltage. More particularly, the method further provides boosting the terminal voltage of the battery in response to the electrode voltage declining below a threshold value.
In a further aspect of the invention, a battery is provided wherein a power sensing circuit senses the electrical charge stored within the battery and generates a conditioned voltage representative of the stored electrical charge to control an indicator exteriorly provided on the battery container.
In addition, a battery is provided wherein a manually activated actuator closes an internal latch to electrically couple internal electrodes of a voltaic cell to exteriorly provided battery terminals.
Furthermore, a battery including a power converter for boosting the terminal voltage of the battery is provided incorporating a power state machine with stop-step oscillator.
Each of these features, individually or in various combinations, are contemplated for enhancing consumer batteries. These and other advantages of the present invention will become apparent in the discussion below.